Is Siberian snow, eastern U.S. cold link legit?

By
Matt Rogers

Yesterday, Jason summarized research performed by Judah Cohen and colleagues (first featured on the NY Times DotEarth blog) which finds above normal fall snow cover in Siberia leads to cold winter over eastern North America. As a long-range forecaster with the Commodity Weather Group in Bethesda, Md., I can confirm that this relationship has some legitimacy.

Figure of relationship between Siberian snow and jet stream pattern courtesy National Science Foundation (NSF). NSF caption excerpt: "When [autumn] snowfall is high in Siberia, the resultant cold air enhances atmospheric disturbances, which propagate into the upper level of the atmosphere, or stratosphere, warming the polar vortex. When the polar vortex warms, the jet stream is pushed south leading to colder winters across the eastern United states and Europe. Conversely, under these conditions the Arctic will have a warmer than average winter."

The illustration above nicely illustrates this relationship, showing how the snow cover enhances the waves that set up the cold patterns like we've seen this year and last year. It is amazing to watch these powerful atmospheric waves propagate across our planet and grow over Siberia. We recently saw such a wave develop in December that helped establish the recent cold, and a new one is expected to move across Eurasia in the coming week. You can watch these waves (way up toward the top of the troposphere) via an excellent National Weather Service animation.

So is this all we ever need to know about seasonal forecasting? Is this relationship the magic bullet?

Unfortunately, two important caveats limit the technique:

First, the prediction of Siberian snow itself is a challenge. I had the honor of sitting on a seasonal forecast panel with Dr. Cohen in late September 2009. For this WeatherBug Seasonal Conference, Dr. Cohen referenced below normal snow in Siberia to support his very warm 09-10 winter outlook for North America. My Commodity Weather Group team was forecasting a cold and snowy winter due to signs that the North Atlantic pattern (NAO) and the emerging El Niño pattern would be supportive. Within weeks of that conference, it began snowing in Siberia. A lot. And by late October, his very warm winter outlook had switched 180 degrees to a cold forecast. The Siberian snow correlation requires knowing what Siberian snow is going to do.

Second, while I have no doubt that enhanced snow pack in Eurasia is amplifying these waves that warm the Polar stratosphere and creating our mammoth blocking patterns (translation: cold U.S., Europe, and Asia winter), something else is initiating these waves. The reason I believe this is that in October 1998, we had well above normal Eurasian snowfall, but we DID NOT have a cold Eastern U.S. winter. Instead, tropical forcing from a powerful La Niña dominated our warm winter weather. The Siberian snow was there, but the waves were not.

The last two winters have featured relentless waves, triggering cold blocking patterns never before seen in modern times. Last winter's Arctic Oscillation (AO) was the lowest in the modern record (back to 1950). The North Atlantic Oscillation (NAO) has averaged negative for an unprecedented 15 straight months now. While the Siberian snow is enhancing the waves and blocking, the waves do not start there, and Siberian snow has been heavier than recent years.

So why the record-setting levels? One might argue that the Siberian snow connection is the "elephant's tail"- an important clue, but not the whole story.

So what is the whole story? Believe it or not, I would like to reference a paper co-authored by Michael Mann and Gavin Schmidt in 2001. In that paper, the authors discuss a correlation between low solar activity during the Maunder Minimum, also known as the Little Ice Age, and strong Arctic and North Atlantic Oscillation behavior that drives colder winters to North America, Europe, and Asia. Page 3 of that short paper shows a map of the colder mid-latitude continents associated with low solar activity and high levels of blocking. The last few years have seen the quietest solar activity since the early 1800s and recent research suggests the sun may even go quieter yet. What was the climate like in the early 1800s?

Think London. Charles Dickens. And then look at the news stories from the last two brutal winters in Europe. To quote another blogger, "we live in interesting times".

It seems that although we may be contributing to "global warming" the Northern Hemisphere still undergoes a normal cooling process during the winter half of the year. Short days, long nights and low solar angle still determine our winter climate.

What could be happening is the way the Ice Ages were explained when I was a boy during the 1950's. An open ice-free Arctic Ocean adds more moisture to high-latitude air masses; this moisture precipitates as snow at high latitudes. Greater continental snow packs start persisting during the summer and develop into continental glaciers which begin moving southward.

Generally the limiting factor for Siberian snow is the dry expanse of the Asiatic land mass. There's no huge moisture source and local sources such as Lake Baikal can't make up for the expansive dry Asiatic steppe. Our inland moisture source, the Great lakes is the EFFECT rather than the cause of the last continental glaciation. In fact, as the glaciers were melting, the amount of water covering interior North America was far greater than today...including the likes of glacial Lake Wisconsin, glacial Lake Agassiz [the current Red River Valley of the North which empties into Hudson's Bay] glacial Lake Missoula, and glacial Lake Bonneville [the remnant of which is today's Great Salt Lake].

It's possible that today's global warming could actually be tipping the balance in the direction of the next continental glaciation event. This could be abetted by our climate mitigation efforts. We may not need to worry about the demise of the polar bears, though future generations may have to worry about polar bears on Long island or even as far south as the Outer Banks.

Thanks for your comments. But you can please not make them bold? Our policy is that only comments from CWG contributors are bold so that they stand out to readers who ask questions. Thanks for understanding.

CWG is on a roll, and recent posts by Wes, Steve Tracton, Jason, and others have all been excellent and generated good comments and discussions.

Pielke's rebuttal to Dr. Cohen offers interesting insight on the limitations of long term modeling and climate forecasting; in fact, Pielke's conclusion seeems to dovetail nicely with yesterday's discussion kicked off by Steve Tracton's post and subsequent discussion of the limitations of short term modeling.

Many of the postings by CWG are excellent.
Is there any archiving of the posts and public responses, and if so, how does one access the archive?

Matt, interesting and insightful post. One quibble though. The suggestion that a new Maunder Minimum-like event would lead to a similar climate as occurred in parts of the northern hemisphere during the early 1800s runs counter to the very blog entry you cited, which reads, "You might be wondering by the way if a new Maunder Minimum would cancel out the effects of increasing greenhouse gases. The answer is no. Dr. James Hansen did the math and says that even a new maunder event would be cancelled out within 7 years by the rising greenhouse gases. It would slow the warming temporarily though…"

Also of note is the fact that 2010 is likely to be the warmest year in recorded history. This warmth has occurred despite the lack of solar activity and harsh winter in the US/Europe/Eurasia last winter and so far this winter. When the Maunder Minimum occurred, greenhouse gas concentrations were much, much lower than they are today. Given that greenhouse gases play a key role in modulating the long-term climate, it's difficult to see a similar variation in solar forcing exerting such an overwhelming role today.

Thanks Andrew! Which blog did I cite? So far, the solar behavior is behaving more like the tamer Dalton Minimum rather than the Maunder. But I would love to see this "math". Mann's paper correlated high latitude blocking to solar activity- not global temperatures, of course. And I believe in the paper, the authors suggested this impact was more regional (Europe and North America) than global.

And since you brought up global temperatures, do you believe all four data sets (HadCRUT, GISS, UAH, RSS) will show 2010 as the warmest year on record?

Andrew, I found the blog reference thanks. So I guess my question to you is: Is the cold and snowy weather in Europe and North America this winter and last winter attributed to global warming as opposed to the cold and snowy weather during the Dalton Minimum? The sun behaving similarly is just a coincidence and the Mann paper therefore not accurate?

As for your question about attribution: there isn't enough data to show that the cold and snowy weather this winter and last winter is due (paradoxically) to global warming. But there have been studies tying wintertime air circulation anomalies to reduction in sea ice cover, as I have detailed at CWG and elsewhere.

I am not arguing that the sun behaving similarly is just a coincidence, or that the Mann et al. paper is incorrect. I am saying that the human GHG forcing should be sufficient to overwhelm a similar solar fluctuation in the future, and that your reference to another "little ice age" was somewhat misleading, considering that Dan Satterfield had stated exactly that.

No real relationship to CO2-induced AGW, no relationship at all to Arctic sea ice, perhaps some relationship to ENSO. One other thing should be noted, AAO is very positive (link is on page above), so that really points to weather, not climate for both AO and AAO.

While I'm heading to bed, those cold Siberian temperatures must be incredibly brutal.

My family moved to Chicago, from the DC area in the summer of 92, just missing the 93 storm, we encountered wind chills that approached -40F in our first winter!

We also had snow and ice so deep my parents cars didn't have the ability to go up the driveway!

Obviously, as a kid approaching middle school ages, I felt like our family was "sent off to siberia." Naturally, my first spring break when I went to Chicago to stay with my family, we got 10 inches of snow on the first day. My third year going back for winter, my first day home, our high for the day was 0F, Never had 1F felt so warm the next day!

We saw last week how tough it can be to predict where snow will fall within the next 24 hours, and these attempts to predict what will happen over the next few years are just a lot of random speculation. It's entertaining in the same way a dorm room bull discussion is, but otherwise is fairly useless.

The global warming crowd went on for years about how we would see less snow, including the 2002 IPCC report that commented on how children might need to be introduced to "virtual" weather effects to understand what snow was. These silly predictions didn't come true, and now they've got their tails between their legs - forced to change their story....yet again

Thanks Andrew. I guess we'll just have to wait and see. If the North American and European winters keep trending colder like the last few now, then perhaps the human forcing offset just isn't working hard enough.

Thanks Sgustaf1. I think it speaks to TGT11's point that the "predicted effect of sea ice loss" are all referenced from recent papers written in 2009 and 2010. Earlier expectations were for winters to continue to trend milder in the Eastern U.S. and Europe with global warming.

It's interesting that you show that predicted effect for Europe and eastern North America via that NOAA link and yet both the UK and US government forecasters were predicting warm winters the last two years. Seems to be a disconnect for sure...

I think right now it is just a theory for why there is so much blocking. The theory seems to make a lot of sense, but time will tell. I would not expect anyone to put that into their operational forecasts. Those were probably more based on ENSO which is better understood. The lack of northern sea ice is a new situation, so probably it be some years to chew on the data before anything definitive comes out that you could base a forecast on.

sgustaf1, thanks for that link. Looks to me like the connection must have some other factors involved. One current problem with their theory is it doesn't explain the delay between freezeup and the arctic high pressure. Mainly it doesn't explain anything about the history of AO negativity. Theories that only fit the current facts but have no use over historical data do not have much value.

Not contributing anything to the weather discussion, but the caption under the top picture mentions the converse incorrectly. The converse of the implication that the warm arctic causes a cold eastern US would be that a cold eastern US CAUSES a warm arctic, which I seriously doubt has been proven. Just being picky ...